Dihydrotestosterone influenced numbers of healthy follicles and follicular amounts of LH receptor mRNA during the follicular phase of the estrous cycle in gilts

The present experiments were conducted to determine androgenic effects on numbers, health, and amounts of gonadotropin receptor mRNA in late developing follicles of gilts. Gilts (n=5 per group) received daily injections of one of the following treatments on days 13-16 or days 13-18 of the estrous cycle: corn oil, 5α-dihydrotestosterone (DHT, 10 mg), flutamide (1.5 g, an androgen receptor inhibitor), DHT (10 mg) plus flutamide (1.5 g), testosterone (10 mg), and testosterone (10 mg) plus flutamide 0.5 g). Ovarian follicles ≥ 5 mm in diameter were evaluated on day 17 or 19, 24 h after receiving the last treatment dose. Follicles were classified as healthy (H), moderately atretic (MA), or very atretic (VA). Treatment with DHT increased (P<0.05) the numbers of H follicles relative to control gilts on days 17 and 19. DHT administration from days 13 to 16 diminished (P<0.05) the amounts of LH receptor (LHR) mRNA in H follicles from day 17 (relative amounts: 1.45±0.33 and 2.72±0.33 for DHT- and vehicle-treated gilts respectively). The effects of DHT on numbers of H follicles and LHR mRNA were not observed in gilts receiving DHT plus flutamide. Androgens did not influence numbers of MA, VA, and total follicles, or follicular estradiol-17β concentrations and amounts of FSHR mRNA. Treating gilts with DHT during follicular recruitment and selection did not induce changes in the numbers of total follicles ≥5 mm, but rather increased the numbers of healthy follicles in this follicular population in association with decreased amounts of LHR mRNA.